Method of making screw and washer assemblies



My 19 1942 H. c. ERDMAN METHOD 0F MAKING scREw AND WASHER Assm'lBLIEs Filed July 23, 1940 2 sheets-sheet 1* 'h lf'lpl I'"|| lu' Il! ,/20

15M@ Mhz/m ATTORNEY May 19f1942 f v `H. c. ERDMAN 2,283,494

METHOD 0F' MAKING vSCREW AND WASHER ASSEMBLIES 4 Filed July 23. 1940 2` sheets-'sheet 2 ATTORNEYS I Patented May 19, "i942 METHOD F MAKING SCREW AND WASW l ASS 115. ze;

Harvey Erdmam Shaker Heights, Ohio, aa-

signor to The National Gompany, Cleveland,

Screw a Manufacturing Ohio, a corporation [et Application eluly 23, 19de, Serial No. 346.9%

(Cle tt-tl) This invention relates to screw and washer assemblies and especially to certain method features thereof, the principal object of the invention being to provide a highly eflicient assembly is satisfactoryffor many uses; it is unsatisfactory for' others because the washer is forced on so tightly vthat when the screw is being applied the washer turns with the screw and often mars the which the lscrew is being inserted. llt is fre.-

' quently the case that a portion of thewasher entends out beyond the head, with the result that it will mar an enameled or other finished surface,

produced 4by a method such that it can be manu- 5 and in such cases an assembly made in this manfactured in large quantities at reduced cost. ner is unsatisfactory and unsuited.

At the present time these assemblies are pro- By still another .method Ithe washer is passed duced by different methods each of which has over the thread next to the head and `is then certain disadvantages either from the standpoint retained in place by a so-called staking or shoulof the assembly itself or from the standpoint of dering process by which a shoulder is thrown up production. By one of the methods in use at the beyond the thread and close to the head. Allpresent time the washer is applied to the shank though this assembly` is satisfactory in the reof the screw (or bolt) after which the thread is Spect that the washer dcan. turn freely on the rolled on the shank and the raised portion o the screw and permits the screw to be plated or heatrolled thread ls relied upon to prevent the-washer treated and, in fact, completed except for the from falling off the screw. While this method i shouldering operation, it .has the disadvantage is satisfactory from a cost standpoint. the asthat-this process requires a separate operation sembly has several disadvantages over an assemtoeilect the staking or shouldering to retain the bly wherein the screw is completed before the washer in place, and this extra operation enwasher ls applied particularly when the screws 2@ tails additional handling of the partsand thus' are to be casehardened, cyanide-hardened, platadds to the cost which is a matter of considered, or heat-treated as when alloy or high'carbon able eonsequenee in the Pl'OdU-elOn 0f large steels are employed. These operations are virquantities which often run into the'millions.' tually impossible if the washer is applied before By the present lnventin the Washer4 1S npthe thread is rolled on the shank of the screw plied after the screw is completed including any since these operations would disadvantageously plating. hardening 0r heet-treating Operelflen affect and in some instances virtually destroy the l to which it may be subjected. end after the Washwasher. For example, the hardening process er is applied it is loose on the shank Or can tum would affect the washers to an extent such that when the screw is being applled t0 the WOrk and they would snap in use. :m the shoulder for retaining it in. place is formed Furthermore, assemblies wherein the washer is Without any eXtra Operation. These results are applied before the shank is threaded have the attained by forming a retaining Shoulder in' the disadvantage that the presence of the washer thread-rolling OperaliOn, the ShOlllder being 0f makes it impossible to thread the shank close up such a nature that the washer can be snapped-0r to the head for otherwise the action o! the rollsprung over it and at the same time there is no ing dies would mutilate if not destroy the washer, danger of the washer accidentally Passing over Additionally, when the thread is relied on to hold the Shoulder in the opposite direction and dropthe washer in place. the washer cannot be defl- Ping 0f! the Screw. nitely positioned up against the head or close to The invention may be further briefly summarit if a considerable portion ofthe length of the ized as consisting in certain steps of the imshank is unthreaded. This is disadvantageous proved method and in improved details of the for certain uses or applications which make it assembly which will be described in the specideslrable if not necessary'that the washer be re eatlen and set fOrth 1n the appended Claimstained closefto the head while the screw is being In the accompanying, sheets of drawings. applied. Fig. l is a conventional representation of the .By another present day lmethod of manufacthread-rolling dies which are utilized in forming turing these assemblies, the washer is applied the thread 0n the screw and which are instru-V after the screw is completed by passing it over mental in forming the Shoulder or ridge which the thread and forcing it onto a shoulder or enacts as a retainer fOr the Washer; largement under the head. While this product 5o Fig. 2 shows a portion of a screw between the thread-rolling dies, the thread and the washerretaining shoulder being shown as completed by the dies and there being shown by dotted lines the shape of the blank prior to the thread-rollsurface of the metal piece or. other part into l lng Operation;

Fig. 3 is a view of the blank prior to the thread-rolling and shoulder-forming operation. a blank of this kind usually being formed from wire by an extrusion process or an upsetting process;

Fig. 4 shows a portion of a completed screw;

Fig, 5 is a similar view with a lock washer slipped in place over the thread and shoulder;

Fig. 6 is a View similar to Fig. 5 showing a. toothed-type lock washer instead of the split type of Fig. 5;

Fig. 7 is a view similar to Fig.,5 showing a screw with a split washer between the head and the shoulder but with a longer unthreaded portion between the thread and the head than is the case with the preceding views;

Fig. 8 is a view similar to Fig. 2 showing a modification of my invention wherein the washer-retaining shoulder is formed a distance from the end of the thread, this form of my invention being useful where the screw has a shank with a shorter thread than is shown in Fig. 2 and a rela-. tively long unthreaded portion and when it is desired to position the washer close to the head rather than allow it to slide freely between the head and the shoulder formed at the inner end of the thread;

Fig. 9 shows the screw of Fig. 8 with the washer in place; and

Fig. l is a perspective view of one of the thread-rolling dies with the part associated therewith for forming the washer-retaining shoulder in cooperation with a similar die and a like shoulder-forming rib.

Verylarge quantities of screw and washer assemblies are being manufactured and sold annually, but generally the major portion of these screws have a diameter on the order of 1A. inch or -g inch. In the drawingsmuch larger screws are illustrated. to more clearly show the features involving the present invention. Accordingly, in practice the washer-retaining shoulder is considerably smaller than herein illustrated, it being in all instances only sumciently high that the washer can be sprung over it and thereafter not come off accidentally but not. high enough to interfere with the insertion of the screw for the full distance into the tapped opening. While my invention iinds its utility in connection with the production of screws muchl smaller than thoseherein illustrated, nevertheless it is adaptable for screws ofany size. My invention can also be employed Iin the production of screw and washer assemblies utilizing any of the standard or specially' formed lock washers, and, if desired, it may be utilized with a plain washer. The washer-retaining shoulder is high enough to serve its purpose of permitting the application of the washer after the thread is formed but is not suiliciently high to prevent any kind of a washer from being passed over the thread and forced over the shoulder regardless of whether or not the washer has a continuous inneredge or periphery. v

Furthermore, it is to be understood that the term screw as used herein is inclusive of a product which is technically a bolt, it being whollyl immaterial to the present invention whether or not the threaded member is adapted to receive a nut.

Referring now to the drawings, l (Fig. 3) represents a typical blank such as may be formed either by an extrusion process or by an upsetting process both of which are well known. The blank the unthreaded part of the shank andwhich may be of variable length, this portion having an outside diameter equal to that of the outside diameter of the threaded portion. The blank also has a reduced portion lc on which the threads are to be rolled and generally a tapered portion ld between the portions i517 and Isc in which portion 35d the thread ends. f

In forming the blank'illustrated in Fig. 3, it may be provided with any desired fvpe of head as well as any relative lengths'of the portions 55h and l5c with the appropriate location of the tapered portion 55d joining them. The complete Y screw l (Fig. 4) is formed by rolling on the reduced portion vlc of the shank the thread la. This is accomplished by thread-rolling dies .shown somewhat conventionally in Fig. 1, these dies including a stationary die Il mounted in a stationary holder i8 and a reciprocating die i9 carried by a reciprocating die holder 20, Fig. l showing vthe blank l5 between the dies at the start of the thread-rolling operation. As is customary, the two dies ll and i9 are provided respectively with thread-forming ribs lla and lawhich for a distance gradually increase in height to about the middle of the die where the ribs have their full height, the ribs having the necessary lead for the angularity of the thread and having a maximum height sufiicient to completely form the thread with the outside diameter of the thread equal to the outside diameter of the portion Ibb of the blank. Ordinarily the thread ends in the tapered portion d and no change whatsoever is made in the portion lb of the blank. In some instances the thread-rolling ribs on the two dies are of the same height and the gradual formation of the thread during the stroke of the movable die is accomplished .by slightly tilting the dies in the respective holders.

In accordance with the present' invention, by a slight change made in the threading dies i1 and l Q a washer-retaining shoulder lh is thrown up or rolledv during the thread-rolling operation to a diameter slightly above that of the thread 5 and of the unthreaded portion 46c (corresponding to the portion l'b of the blank) which shoulder, as before stated, permits a washer to be n sprung over it onto the unthreaded portion of the screw next to the head and is not too high for 5g that purpose but still high enough to prevent the lwasher from accidentally falling off the screw.

Drdinarily, i. e., in forming screws without the washer-retaining shoulder, the distance between the dat faces of the dies extending beyond the thread-rolling ribs is equal to the diameter of the portion lbof the blank, i. e., the portion not to be threaded. That is to say, the portions of the dies projecting beyond the thread-forming ribs are :dat and the portion lb of the blank @o rolls on these fiat faces so that no metal whatever is thrown up beyond the tapered portion idd of the blank. However. to bring about the formation of the washer-retaining` shoulder lh during the thread-rolling operation, it is only necessary to relieve or cut back the metal beyond the thread-forming ribs as shown at Ilb and l9b (Fig. 2) so thatthe portions of the ribs forming the inner end of the thread will roll up the metal of the tapered portion italof the blank and diso place it toward the head in the form of the shoulder llib, as clearly illustrated in Fig. 2. Thus by this change in the dies the thread is rolled in the blank and the shoulder is formed in the same operation without adding anything has a head Ia and a portion i519 which is to be to the cost of the nished product and without in any way adversely affecting the strength and 22d corresponding to the shoulder |6b oi Figs. 4`

and 5. but in this instance there is located between the head and the shoulder 22d a lock washer 23 toothed at its inner periphery. As previously stated, the split washer 2| (Fig. 5) and the toothed washer 22 (Fig. 6) are typical of a group of washers commonly employed, and other washers of standard or special shape may, if desired, be employed just as effectively as those illustrated, as, for example, washers toothed at their outer periphery and plain or continuous 'at their inner periphery or washers toothed at both peripheries, and plain washers which may be round or continuous at both peripheries.

The screw designated 24 in Fig. l is similar to the screws illustrated in Figs. 4, 5, and 6 except that it has a longer unthreaded portion 24a between the head and the washer-retaining shoulder 24h, the latter being formed in precisely the same manner as the washer-retaining shoulder 22d of Fig. 6 and the shoulder |6b of Figs. 4 and 5. In this instance the washer, as in Fig. 5, is a split washer 2|. In this case the washer is free (prior to and during the application of the screw to the threaded hole in the work piece) to move between the shoulder 2lb and the head 24e. This is not objectionable in some instances, but, as previously stated, for certain uses where the thread is short or where the screw 'has a long unthreaded portion between the head and the thread it is desired that while the screw is being applied to the work piece the washer be held up close to the head.

In accordance with a modified form of my invention I am enabled during the thread-rolling operation toprovide a rolled washer-retaining shoulder as clcse to the head as desired or at any desired distance from the inner end of the thread, and screws of this type are illustrated in Figs. 8 and 9 where they are designated 25. This screw has a thread 25a, a long unthreaded forming ribs ,30 of thel die extensions 28 and 29 the inner faces of these die extensions engage shank portion.-25b between the thread and the head 25o and close to the head is a rolled washer.. retaining shoulder 25d for holding in place between this shoulder and the head any desired washer, here shown as a split lock washer 2|. This shoulder is formed in the thread-rolling operation by clamping in the stationary and movable dieholders alongside the stationary and movable dies designated -26 and 21 respectively in Fig. 8 extensions. 28 and 29 provided with shoulder-rolling ribs 30 located at the proper distance with respect to the thread-rolling ribs 3| and cooperating to form at the desired distance from the head 25e the washer-retaining shoulder- 25d. These shoulder-rolling ribs 30, unlike the thread-rolling ribs, are without leads and they vpress or roll a groove 25e in the blank and the metal displaced in forming this groove flows in one direction, i. e., toward the head, this being accomplished by forming a relie! or cutting away the metal on the inner faces of the die extensions 28 and 29 on the side of the rib 30 toward the head, this relief being designated 32 in Fig. 8. On the other side ot the shoulder- 76 the shank oi' the blank the same as the inner faces o! the dies proper so that in forming the groove 25e the metal is free to flow only inwardly toward the head, as clearly indicated in Fiss. 8 and 9.

By reference to Fig. 10 it will be noted that the grooveand shoulder-rolling rib 30 oi the composite die. like the thread-rolling ribs 3|, is oi?l gradually increasing height from the end .where the rolling operation starts to about the center of the die and then is of uniform height to the other end. This will be true of both composite dies. Oi course both of thedies are similarly formed. The relief 32 of the die extensions 28 and 29 may be of uniform depth for the full length of the rib 3u but, as illustrated in Fig. 10, it is ilush with the unrelieved portion of the face of the die at the end where the rib 30 is of minimum height and gradually increases in depth to the opposite end. Thus the action of the grooveand shoulder-rolling ribs 30 of the two dies is exactly the same as the action of the thread-rolling ribs 3| in the respect that the metal forming the groove 25e and the shoulder 25d is displaced gradually from the start to about the middle of the thread-rolling operation from which point to the end of the threadrolling operation theribs 30 and 3| have a ysocelled ironing or smoothing action. It will be understood that with the screw illustrated in Figs. 8 and 9 the diameter of the unthreaded portion oi the shank between the head and the shoulder 25d is the same as the diameter of the unthreaded portion between the groove 25e and thethread and the sameas the external diameter of the threaded portion 25a.

Thus it will be seen that the objects of the invention stated in the early part of this specication are attained very eiectively by this invention. Not onlydo .I regard as new my improved process wherein the washer-retaining shoulder is rolled on the blank simultaneously with the rolling of the thread, but I regard as new also the resulting product, i. e., a screw having a rolled thread and having between the thread and the head of the screw either at the inner end of the thread or at any desired distance from the inner end of the thread a rolled washer-retaining shoulder, and I therefore aim in my claims to cover all modifications which do not involve a departure from the spirit and the scope of the invention in its broadest aspects.

Having thus described my invention, I claim:

1. The method of forming a screw adapted for .a screw and washer assembly which comprises cation of the washer to the screw and the rolled shoulder being somewhat higher than the rolled thread so that after 'the screw is completed a washer :maybe moved over the thread and shoulder'and retained between the shoulder and the head of the screw.

2. The method of forming a screw' adapted for a screw and washer assembly which comprises rolling a helical thread on a portion of a headed blank and in the same operation rolling a continuous annular washer-retaining shoulder at the inner end of the thread, the rolling of the helical thread and annular shoulder being done prior t the application of the washer to the screw and the rolled shoulder being somewhat higher than the rolled thread so that after the screw is completed a washer may be moved over the thread and shoulder and retained between the shoulder and the head of the screw.

3. The method of forming a screw adapted for a screw and washer assembly which comprises rolling a helical thread on a portion of a headed tained between the shoulder and the head of the screw. a

4. The method of forming a screw from a blank having a head. a portion of reduced diameter to be threaded, and a portion of larger diameter between the iirst named portion and' the head and adapted to be left unthreadedl which comprises rolling a helical thread on the portion of reduced diameter and in the .same operation forming a continuous annular shoulder on the portion of larger diameter, the rolling of the helical thread and annular shoulder being done prior to the application of the washer to the screw and said shoulder being suiiiciently higher than the external diameter of the thread and of said portion of larger diameter that when a washer is passed over the thread and forced over the shoulder it will be retained by the latter vbetween it and the head. l

5. The method of forming a screw from a blank having a head and a shank with aportion of reduced diameter adapted to be threaded, a portion of larger diameter next to the head, and a tapered portion between the two ilrst named portions, which comprises rolling a. thread on the portion of reduced diameter and in the same operation rolling up the metal of the tapered portion so as to form a shoulder suiliciently higher than the external diameter cf the thread and of the portion of the shank of larger diameter that a washer can be passed over the thread and forced over the shoulder and thereafter be retained between the shoulder and the head.

6. The method of forming a screw from a blank having a shank with a portion of reduced diameter adapted to be threaded and a portion of larger diameter between the first named portion and the head, which comprises rolling the thread on the portion of reduced diameter and at the same timerolling a groove in the portion of larger diameter and causing the metal displaced in forming the groove to produce a shoulder somewhat larger than the diameter of the larger portion of the shank so that a washer can be passed over the thread and forced over said shoulder to be retained by the latter between said shoulder and the head.

'1. The method of making screw and washer assemblies which comprises rolling a helical .thread on a headed blank and in the same operation rolling on the blank a continuous annular washer-retaining shoulder which is somewhat highcr than the rolled thread, and then -moving over the thread and shoulder a washer of a size tobe retained on the screw between the shoulder and head thereof.

8. The method o1' making screw and washer assemblies which comprises rolling a helical thread on a portion of a headed blank and in the same operation rolling at the inner end of the thread a continuous annular washer-retaining shoulder which is somewhat higher than the rolled thread. and then moving over the thread and shoulder a washer of a size to be retained on the screw between the shoulder and head thereof.

9. The method of forming a screw from a blank having a head and a shank with a por-v tion of reduced diameter adapted to be threaded, a portion of larger diameter next to the head, and a. tapered portion between the two iirst 'named portions, which comprises rolling a lo. The method of forming a screw from a blank having a shank with a portion of reduced diameter adapted to be threaded and a portion of larger diameter between the iirst named portion and the head, which comprises rolling the thread on the portion of reduced diameter and at the same time rolling a groove in the portion of larger ldiameter and causing the metal displaced in forming the groove to produce a shoulder somewhat larger than the diameter of the larger portion of the shank, and then moving over the thread and shoulder a washer of a size to be retained on the screw between the shoulder and head thereof. l I

HARVEY C. ERDMAN.

DISCLAIMER 2,283,494.Harvey10. Erdman, Shaker Heights, Ohio. METHOD or MAKING SCREW AND WASHER AssEMBLms; Patent datedMay 19, 1942. Disclaimer filed ugust 10, 1944, bythe assignee, The National Screw 2 Manufaeturng `0ompmy. 1 Hereby enters this disclaimer to claims 1, 2, 3, 4, 7, and 8 of said patent.

[Oficial Gazette September 5, 1944.] 4 

